Induction coil mounting



y 1944- H. F. OBERGFELL 2,348,404

INDUCTION COIL MOUNTING Filed June 11, 1942 INVENTOR- HERBERT F. OBERGFELL ATTORNEY I Patented May 9 1944 INDUCTION c011. MOUNTING Herbert F. Obergfell, River Forest, 111., assignor to Automatic Electric Laboratories, Inc., a corporation of Delaware Application June 11, 1942, Serial No. 446,635

3 Claims. (Cl. 175-361) This invention relates to mounting arrangements for induction coils in general but more particularly to a mounting arrangement for an induction coil having moulded plastic spool heads and the principal object of the invention resides in the provision of an improved method of mounting an induction coil having plastic spoolheads so that the plastic spool heads will not shatter, or break, when the induction coil is subjected to extreme shocks.

It is now customary in telephone sets to use the improved induction coils having spool heads formed of a plastic insulation material such as a phenolic condensation product known to the trade as Bakelite. This customary use has proven very satisfactory except when the telephone sets were placed on board ships and were subjected to extreme shocks, or concussions, such as the explosion of bombs or the firing of heavy guns. Usually a small lip or a hole in the plastic spool head was provided for mounting the induction coil and in a good many cases the shocks broke, or shattered, the plastic spool heads thereby rendering the telephone set unusable. The shock stress in this type of mounting was concentrated more or less on only a very small portion of the plastic spool resulting in the breaking or shattering of the moulded plastic. It was, therefore, found necessary, if this plastic type of induction coil is to be used on board ship, to find some method of mounting the moulded plastic induction coil so that the plastic spool heads would not shatter or break when subjected to extreme shocks. In accordance With the present invention, metal side members are clamped around the outside surfaces of the side and end portions of the plastic spool heads to firmly hold and wedge the induction coil between the metal side members. In this manner the greater outside portion of each spool head is clamped, or wedged, by the metal side members to thereby present a large area over which the shock stress is uniformly distributed. Due to this distribution it was found that the plastic induction coil could withstand etreme heavy shocks when mounted in accordance with the present invention.

The invention is disclosed in the accompanying drawing in which Fig. 1 shows a top view, Fig. 2 a side view and Fig. 3 an end view of the assembled mounting arrangement. Fig. 4 shows a partial exploded view with the respective parts near their assembled positions. Fig. 5 shows a side View of the two-piece induction having plastic spool heads, or ends.

Referring now to the drawing, the induction coil comprises an upper portion and a lower portion. The upper portion comprises a laminated iron core [4 shown part in full lines in the section portion and in dotted lines in the remaining portion of Fig. 5. On each end of the laminated iron core I4 is a plastic moulded spool head H formed of a plastic insulation material such as a phenolic condensation product known to the trade as Bakelite. Each spool head H is moulded with parallel and converging side surfaces and with I a cut-out portion 13. Metal terminal pins 12 are imbedded in the plastic spool heads H for terminating the ends of the coil windings it and other electrical connections. The lower portion comprises plastic ends I7 and the laminated iron member i8 for completing the magnetic circuit for the induction coil. As will be noted in Fig. 5 a small air gap is provided between the two laminated" iron members I4 and 18. The induction coil is made in two portions to permit easy winding of the upper portion.

In order to mount this induction coil so as to prevent breaking of the plastic spool heads when subjected to extreme shocks two metal side members 3 are placed on either side of the induction coil. Each side member 3 is shaped to fit the side and converging surfaces of the spool heads. The side members 3 are then bolted together by means of bolts 6 thereby clamping or wedging the induction coil in place between the two side members 3. The side members 3 engage and. clamp the parallel side and converging surfaces of the spool head, thereby distributing the holding or clamping force over a large area of each spool head, such area comprising the greater portion of the outside surfaces of the spool heads.

Metal end members 4 are provided with tapped holes for bolt 5 and with a curved lug to fit the cut-out portion It in the spool heads H. These end members 4 are placed on top of the metal side members 5; and then bolted to the base i by means of washers 2 and bolts 5 screwed into the tapped holes in the end members i. The mounting strain is on the bolt 5, the metal end members i, and the metal side members 3.

Let it be assumed now that the base i, which may be a face plate of a wall telephone set, is subjected to a severe shock, or concussion, such as may happen on board ship due to heavy explosions or the like. The induction coil is fairly heavy and represents an appreciable amount of mass which has a tendency, in response to the shock, to be moved suddenly in much the same manner as if it were given a violent push. In this case since the plastic spool heads are firmly clamped on their parallel and converging side surfaces by the side members 3 over the greater part of their outside surfaces, the shock stress is distributed over a sufficient area of each spool head to prevent the same from shattering or breaking. In addition the end members 4 and Washers 2 also engage outside surfaces of the plastic ends of the induction coil to assist in holding the induction coil in place. Due to this clamping of the induction coil spool heads, the shock stress is transferred from the plastic spool heads to the metal side and end members 3 and 4, respectively, and bolt 5 which are of sufficient strength to withstand the shock.

Having described the invention, what is considered new and is desired to be protected by Letters Patent is set forth in the following claims.

What is claimed is:

l. A shock-proof mounting including an induction coil having a laminated core and a spool head of moulded plastic on each end thereof, each spool head having parallel side surfaces and converging end surfaces extending from said parallel side surfaces, two metal side members having corresponding parallel side and converging surfaces shaped to fit the side and converging surfaces of the moulded plastic spool heads of the induction coil, means for clamping said side members against the surfaces of said plastic spool heads to firmly hold said induction coil between said side members, said clamping means causing said converging surfaces of said spool heads to be firmly wedged by a wedging action in between said members, metal end members located on top of the ends of said side members and in engagement with top portions of said plastic spool heads thereby forming with said side members a partial metal enclosure for said induction coil, a mounting base for said induction coil, and means for mounting said induction coil on said base so that said partial metal enclosure is arranged to distribute the shock stress on said side and converging surfaces and top portions of the plastic spool heads to prevent shattering of the plastic spool heads when subjected to severe shock.

2. A shock-proof mounting including an induction coil having a laminated core and a spool head of moulded plastic on each end thereof, each spool head having parallel side surfaces and converging end surfaces extending from said parallel side surfaces, two metal side members having corresponding parallel side and converging surfaces shaped to fit the parallel side surfaces and converging end surfaces of said spool heads, and means for clamping said side members together and against the corresponding surfaces of said spool heads, said clamping means causing said converging surfaces of said spool heads of said induction coil to be firmly wedged by a wedging action in place between said members to thereby distribute the shock stress over said side and end surfaces of said spool heads and prevent shattering of the plastic spool heads when subjected to severe shock.

3. The combination of an induction coil having a Wedge-shaped spool head on each end thereof, two mounting side members each shaped to fit the contour of one of the sloping wedge surfaces on each of said spool heads, and means for clamping said two side members around said induction coil at both ends, said wedge-shaped spool heads creating a wedging action against said side members in response to tightening said clamping means to thereby distribute the clamping pressure evenly over a large area of the surfaces of both said spoolheads.

HERBERT F. OBERGFEIL. 

